This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We have used antibodies to stem cell proteins known to be central to maintenance and differentiation to pull down complexes associated with these proteins. Mass Spectrometry analysis (MudPit) have been used to identify the components of these complexes. This allows us to analyze those associated proteins with respect to stem cell function.